Recently, display devices having a large-sized screen have become widespread, and are in common use at conferences, presentations, seminars and so on.
There are various displays such as a liquid crystal display or a plasma display. An appropriate one is selected from among the various displays in accordance with the available space or the number of participants when used. In particular, a projector, which is able to project an image to a projection surface such as a screen to be enlarged and displayed thereon, is the most widespread large-screen display because it is relatively reasonable cost-wise and superior in portability (that is, it is small and lightweight).
Recently, greater communication is needed in various situations. In this regard, there are many small meeting rooms or partitioned discussion spaces in an office, for example. Conferences or meetings using a projector are often held in such areas.
In addition, urgent or emergency meetings are often held in an open space such as a walkway while projecting and displaying information on the wall thereof when meeting rooms are occupied.
As the projector described above, a projector having a high luminance discharge lamp as a light source is known. The lamp is, for example, an extra-high-pressure mercury lamp. In recent years, a solid-state light-emitting device such as red, green and blue light-emitting diodes (LED) or an organic electro-luminescence has been developed and proposed as a light source.
For example, JP2010-217566A discloses a light source device including three light-emitting devices such as an R (Red) light-emitting device, G (Green) light-emitting device and B (Blue) light-emitting device. The R light-emitting device includes R (Red) phosphor and an R light source which excites the R phosphor. The G light-emitting device includes G (Green) phosphor and a G light source exciting the G phosphor. The B light-emitting device includes B (blue) phosphor and a B light source exciting the B phosphor.
A light source device which is capable of generating RGB light using only one light source is also considered (refer to, for example, JP 2004-341105A). The light source device disclosed in JP2004-341105A includes a solid-state light source emitting ultraviolet rays and a light source device having a light converter which converts the ultraviolet rays to visible light by phosphor. A projector using the light source device is also disclosed in JP2004-341105A. The light converter includes a phosphor wheel having a transparent disk (transparent base material) and three phosphor areas of RGB (area for red phosphor layer, area for green phosphor layer and area for blue phosphor layer) provided on the transparent disk to be divided into three in the circumferential direction thereof.
In the light source device, the phosphor wheel rotates by the motor. The ultraviolet rays are incident on the three phosphor areas of RGB in series according to the rotation of the transparent disk. Therefore, visible fluorescent light of RGB is generated in series from the three phosphor areas of RGB per predetermined period. In addition, the projector having the light source device forms images of RGB in series per predetermined period by a microdisplay. The projector, on the other hand, emits three kinds of visible light of RGB generated by the light source device. The three kinds of visible light of RGB generated in series are irradiated on the RGB images formed on the microdisplay in a predetermined period in order. Accordingly, the projector sequentially magnifies and projects each color image formed by the microdisplay.
Herein, only one type of the solid-state light source of ultraviolet rays is used in the light source device (illuminant system), but the phosphor area (phosphor layer) of the phosphor wheel is divided into three segments (area for red phosphor layer, area for green phosphor layer, area for blue phosphor area). Therefore, the construction of the phosphor wheel is complicated.